X-ray tube electron sources
First Claim
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1. An electron source for an X-ray scanner comprisingan emitter support block having a first side and a second side;
- an electron-emitting region formed on the emitter support block and arranged to emit electrons;
an electrical connector arranged to connect a source of electric current to the electron-emitting region;
at least one focusing element arranged to focus the electrons towards an anode and having a lower portion extending parallel to said first or second side and a curved upper portion extending upward from the lower portion, beyond the electron-emitting region, and curving back toward the electron-emitting region;
an extraction grid between said emitter support block and the at least one focusing element, wherein the at least one focusing element is held at an electrical potential that is negative with respect to the extraction grid; and
heating means arranged to heat the support block.
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Abstract
An electron source for an X-ray scanner includes an emitter support block, an electron-emitting region formed on the support block and arranged to emit electrons, an electrical connector arranged to connect a source of electric current to the electron-emitting region, and heating structure arranged to heat the support block.
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Citations
15 Claims
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1. An electron source for an X-ray scanner comprising
an emitter support block having a first side and a second side; -
an electron-emitting region formed on the emitter support block and arranged to emit electrons; an electrical connector arranged to connect a source of electric current to the electron-emitting region; at least one focusing element arranged to focus the electrons towards an anode and having a lower portion extending parallel to said first or second side and a curved upper portion extending upward from the lower portion, beyond the electron-emitting region, and curving back toward the electron-emitting region; an extraction grid between said emitter support block and the at least one focusing element, wherein the at least one focusing element is held at an electrical potential that is negative with respect to the extraction grid; and heating means arranged to heat the support block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An electron source for an X-ray scanner comprising
an emitter arranged to emit electrons, wherein the emitter has a first side and a second side; -
an electrical connector arranged to connect a source of electric current to the emitter; heating means arranged to heat the emitter; an extraction grid; control means arranged to control the relative electrical potential between the grid and the emitter to control extraction of electrons from the emitter wherein the grid includes an extraction region through which electrons can pass; at least one focusing element arranged to focus the electrons towards an anode and having a lower portion extending parallel to said first or second side and a curved upper portion extending upward from the lower portion, beyond the extraction grid, and curving back toward the extraction grid, wherein the at least one focusing element is held at an electrical potential that is negative with respect to the extraction grid; and a shielding region arranged to intercept heat radiated from the emitter or the heating means. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification